The proposed work involves physical-chemical characterization of repeated DNA base sequences in a variety of land plants. This information concerning the sequence organization of higher plant genomes will be used to probe the growth of the genome and the evolution of land plants. The information gained in this work might also be applicable to questions in gene regulation if the Britten-Davidson model for control of transcription is correct. We have detected DNA sequences in the mainband component in CsCl gradients which are homologous with satellite DNA sequences in the muskmelon. These satellite-homologous sequences have also been detected in three other cucurbit species. This observation is interpreted as evidence for the translocation of satellite DNA sequences throughout the genome where they are recognized as dispersed and intermediately repetitive DNA sequences. This work is continuing with related species which also contain the dispersed satellite-homologous sequences.